Defining a pragmatic semantic description of SVG content.

Defining a pragmatic semantic description of SVG content.
(for people who use screenreaders and search engines.)

The attached is slightly long at 500 words, and may well demonstrate  
my ignorance rather than any great truth. Please treat it delicately,  
as it is terse and the expression may be less than ideal.

the short version is:
Please could interested parties including the SVG & SWIG WGs comment  
and contribute examples for a Techniques Document that would be  
helpful to screenreader developers and SVG authors?

cheers

Jonathan Chetwynd
Accessibility Consultant on Media Literacy and the Internet

Defining a pragmatic semantic description of SVG content.
(for people who use screenreaders and search engines.)

How can we develop a common language to describe graphics and the  
text used to label them?
One that is simple and easy to explain and use.

Contents:

Current situation
        Root title
        Title
        Text
        Schema
        Guideline for screenreader developers

Planning for the future.
        Techniques Document for improving access
        Maps
        Graphs:
        More

Current situation

The current state of published SVG ensures that much of the content  
is only purposeful to a sighted individual with an enabled user agent.

        Root title

Many SVG documents including some well known and used example  
libraries [1]. fail to provide <title> data. According to the  
specification this should be the first element after the <svg> element 
[2]
People using search engines and screen readers may have difficulty  
finding or interpreting these files.

        Title

Where title is provided, the author may be expected to have  
understood the purpose, and generally this content may be useful to  
people using screenreaders or search engines.

        Text

Text in SVG is not semantically rich as in other languages such as  
HTML. The screenreader user may experience problems[3] understanding  
spoken text, as it is likely to be context specific in a graphical  
environment such as SVG.

        Schema

Whilst it is true there is at least one schema[4] for describing  
GUIs, afaik none is widely adopted or recognized as a standard.

        Guidelines for screenreader developers

I am not aware of published guidelines, working with Charles Chen of  
FireVox I proposed the following:

1. Check if the first child is a <title> and it has content, not just  
whitespace, then speak it, else say “untitled SVG”[5]

then only "onfocus" ie when the user keyboard navigates with the tab  
key to each of the 4 cases in the testcase [6].

1. Check if the first child is a <title>, if so, speak it...
and if
2. The child is <a> with an xlink:title attribute: Speak the  
xlink:title attribute, possibly adding "linking to" between 1 & 2

or

1. Check if The child is <text>: If it has content, speak it.
and if
2. The child is <a> with an xlink:title attribute: Speak the  
xlink:title attribute, possibly adding "linking to" between 1 & 2

Planning for the future.

It is evident that if we wish to engage people who use screenreaders  
or search engines we need to enhance the semantic content of SVG.  
This will require commonly agreed standards, guidelines and a  
techniques document if screenreader developers and SVG authors are to  
understand the requirements.

        Techniques Document for improving access

Please could interested parties including the SVG WG contribute  
examples for a Techniques Document that would be helpful to  
screenreader developers and SVG authors?

        Maps:

Would it be helpful to recommend that nameplaces are in alphabetical  
order, as in a gazetteer?
This could be helpful as the order would be understood by many.[7]

        Graphs:
A paradigm example?
how to label axis, etc....

        More:


http://www.croczilla.com/svg/samples/
http://www.w3.org/TR/SVG11/struct.html#DescriptionAndTitleElements
http://www.carto.net/williams/yosemite/index.svg
http://www.peepo.co.uk/temp/gui-schema#
http://upload.wikimedia.org/wikipedia/commons/b/b7/Black-cloud.svg
http://www.peepo.co.uk/temp/focusable.svg
http://upload.wikimedia.org/wikipedia/commons/a/a5/ 
Map_of_USA_with_state_names.svg

Received on Monday, 28 January 2008 11:36:25 UTC